Systems and methods for spatial prediction

ABSTRACT

Systems, methods, and instrumentalities are disclosed relating to intra prediction of a video signal based on mode-dependent subsampling. A block of coefficients associated with a first sub block of a video block, one or more blocks of coefficients associated with one or more remaining sub blocks of the video block, and an indication of a prediction mode for the video block may be received. One or more interpolating techniques, a predicted first sub block, and the predicted sub blocks of the one or more remaining sub blocks may be determined. A reconstructed first sub block and one or more reconstructed remaining sub blocks may be generated. A reconstructed video block may be formed based on the prediction mode, the reconstructed first sub block, and the one or more reconstructed remaining sub blocks.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/535,043, filed Sep. 15, 2011, the contents of whichare hereby incorporated by reference herein.

BACKGROUND

Digital video capabilities may be incorporated into a wide range ofdevices, including, but not limited to, digital televisions, digitaldirect broadcast systems, wireless broadcast systems, personal digitalassistants (PDAs), laptop or desktop computers, digital cameras, digitalrecording devices, video gaming devices, video game consoles, cellularor satellite radio telephones, and the like. Digital video devices mayimplement video compression techniques, such as those described in thestandards defined by MPEG-2, MPEG-4, ITU-T H.263 or ITU-T H.264/MPEG-4,Part 10, Advanced Video Coding (AVC), and extensions of such standards,to transmit and receive digital video information more efficiently.

Video compression techniques may perform spatial prediction and/ortemporal prediction to reduce or remove redundancy inherent in videosequences. For block-based video coding, a video frame or slice may bepartitioned into blocks. Each block may be further partitioned. Inaccordance with various coding techniques, blocks in an intra-coded (I)frame or slice may be encoded using spatial prediction with respect toneighboring blocks. Blocks in an inter-coded (P or B) frame or slice mayuse spatial prediction with respect to neighboring blocks in the sameframe or slice or temporal prediction with respect to blocks in otherreference frames.

SUMMARY

Systems, methods, and instrumentalities are disclosed relating to intraprediction of a video signal based on mode-dependent subsampling. Aprocessor may receive a block of coefficients associated with a firstsub block of a video block, one or more blocks of coefficientsassociated with one or more remaining sub blocks of the video block, andan indication of a prediction mode for the video block. The processormay determine one or more interpolating techniques based on theprediction mode and a predicted first sub block using intra predictionbased on the prediction mode. The processor may add the predicted firstsub block to generate a reconstructed first sub block. The processor maydetermine the predicted sub blocks of the one or more remaining subblocks based on the one or more interpolating techniques for the videoblock. The processor may add the predicted sub blocks of the one or moreremaining sub blocks to generate one or more reconstructed remaining subblocks. The processor may form a reconstructed video block based on theprediction mode, the reconstructed first sub block, and the one or morereconstructed remaining sub blocks. The video block may be a lumacomponent or a chroma component of a video signal.

The reconstructed first sub block may be generated by inverse quantizingand inverse transforming the coefficients associated with the first subblock using a first set of inverse quantization and inversetransformation parameters. The first set of inverse transformation andinverse quantization parameters may be associated with a shape-adaptivediscrete cosine transformation. Inverse transforming the coefficientsassociated with the predicted first sub block may include a non-squareshaped transform.

The one or more reconstructed remaining sub blocks may be generated byinverse quantizing and inverse transforming the coefficients associatedwith the one or more remaining sub blocks using a second set of inversequantization and inverse transformation parameters. The second set ofinverse transformation and inverse quantization parameters may beassociated with a shape-adaptive discrete cosine transformation. Inversetransforming the coefficients associated with the one or more remainingsub blocks may include a non-square shaped transform. The first set ofinverse quantization and inverse transformation parameters may be thesame as or different from the second set of inverse quantization andinverse transformation parameters.

A first portion of the one or more reconstructed remaining sub blocksmay be generated and, subsequent to generating the first portion of theone or more reconstructed remaining sub blocks, a second portion of theone or more reconstructed remaining sub blocks may be generated based atleast partially on the generated first portion.

A video block and a prediction mode may be received. The video block maybe subsampled based on the prediction mode to generate a first sub blockand one or more sub blocks comprising missing pixels. A predicted firstsub block may be determined using intra prediction based on theprediction mode. The first sub block may be reconstructed to generate areconstructed first sub block. The prediction mode and the reconstructedfirst sub block may be interpolated to obtain the predicted one or moresub blocks comprising missing pixels. The one or more sub blockscomprising missing pixels may be reconstructed to generate reconstructedone or more sub blocks. A reconstructed video block may be formed basedon the reconstructed first sub block, the reconstructed one or more subblocks comprising missing pixels, and the prediction mode. The videoblock may be a luma component or a chroma component of a video signal.

The first sub block may be reconstructed based on a first set oftransformation and quantization parameters to generate a reconstructedfirst sub block and the one or more sub blocks comprising missing pixelsmay be reconstructed based on a second set of transformation andquantization parameters to generate reconstructed one or more subblocks. The first set of transformation and quantization parameters maybe the same as or different from the second set of transformation andquantization parameters.

A first portion of the one or more sub blocks comprising missing pixelsmay be reconstructed based on a second set of transformation andquantization parameters and, subsequent to reconstructing the firstportion of the one or more sub blocks comprising missing pixels, asecond portion of the one or more sub blocks comprising missing pixelsmay be reconstructed based at least partially on the reconstructed firstportion. The reconstruction of the second portion of the one or more subblocks comprising missing pixels may utilize a third set oftransformation and quantization parameters, and the third set oftransformation and quantization parameters may be the same as the firstset of transformation and quantization parameters or the second set oftransformation and quantization parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of a block-based videoencoding system.

FIG. 2 is a block diagram illustrating an example of a block-based videodecoder system.

FIG. 3 is a diagram illustrating an example of prediction modes that maybe supported.

FIG. 4 is a diagram illustrating an example of horizontal prediction fora 4×4 block.

FIG. 5 is a diagram illustrating an example of 34 directional intraprediction modes.

FIG. 6 is a diagram illustrating an example of a non-directional intraprediction mode.

FIG. 7 is a diagram illustrating an example of Short Distance IntraPrediction on a 32×32 block.

FIG. 8 is a block diagram illustrating an example of an encoderimplementing Mode-Dependent Subsampling Intra Prediction (MDS-IP).

FIG. 9(A) is a diagram illustrating an example of a horizontalprediction mode.

FIGS. 9(B)-9(D) are diagrams illustrating examples of a horizontalprediction mode interpolation and predicting process.

FIGS. 10(A)-10(C) are diagrams illustrating examples of a verticalprediction mode interpolation and predicting process.

FIG. 11(A) is a diagram illustrating an example of a diagonal predictionmode.

FIGS. 11(B)-11(D) are diagrams illustrating examples of a diagonalprediction mode interpolation and predicting process.

FIGS. 12(A)-12(D) are diagrams illustrating examples of a diagonalprediction mode interpolation and predicting process.

FIGS. 13(A)-13(D) are diagrams illustrating examples of a diagonalprediction mode interpolation and predicting process.

FIGS. 14(A)-14(D) are diagrams illustrating examples of a diagonalprediction mode interpolation and predicting process.

FIGS. 15(A)-15(C) are diagrams illustrating examples of a diagonalprediction mode interpolation and predicting process.

FIG. 16(A) is a diagram illustrating an example of a non-directionalprediction mode.

FIGS. 16(B)-16(D) are diagrams illustrating examples of anon-directional prediction mode interpolation and predicting process.

FIGS. 17(A)-17(D) are diagrams illustrating examples of anon-directional prediction mode interpolation and predicting process.

FIG. 18 is a diagram illustrating an example of a communication system.

FIG. 19A is a system diagram of an example communications system inwhich one or more disclosed embodiments may be implemented.

FIG. 19B is a system diagram of an example wireless transmit/receiveunit (WTRU) that may be used within the communications systemillustrated in FIG. 19A.

FIGS. 19C, 19D, and 19E are system diagrams of example radio accessnetworks and example core networks that may be used within thecommunications system illustrated in FIG. 19A.

FIG. 20 is a block diagram illustrating an example of a decoderimplementing Mode-Dependent Subsampling Intra Prediction (MDS-IP).

DETAILED DESCRIPTION

Video coding systems may be used to compress digital video signals toreduce the storage and/or transmission bandwidth of such signals.Various types of video coding systems, such as, but not limited to,block-based, wavelet-based, and object-based systems may be deployed.Examples of block-based video coding systems include, but am not limitedto the MPEG1/2/4 part 2, H.264/MPEG-4 part 10 AVC and VC-1 standards.

FIG. 1 is a block diagram illustrating an example of a block-based videoencoding system 100. The input video signal 102 may be processed blockby block. For example, the video block unit may be 16 pixels by 16pixels (e.g., a macroblock (MB)). A video coding standard such as HighEfficiency Video Coding (HEVC) may be used. In HEVC, extended blocksizes (e.g., which may be referred to as a “coding unit” or CU) may beused to compress high resolution (e.g., 1080p and beyond) video signals.For example, a CU in HEVC may be up to 64×64 pixels and down to 4×4pixels. A CU may be partitioned into prediction units (PU), for whichseparate prediction implementations may be applied. Each input videoblock (e.g., MB, CU, PU, etc.) may be processed by using a spatialprediction unit 160 and/or a temporal prediction unit 162.

Spatial prediction (or intra prediction) may use pixels from the codedneighboring blocks in the same video picture/slice to predict thecurrent video block. Spatial prediction may reduce spatial redundancyinherent in the video signal. Temporal prediction (or inter predictionor motion compensated prediction) may use pixels from the already codedvideo pictures to predict the current video block. Temporal predictionmay reduce temporal redundancy inherent in the video signal. Temporalprediction for a given video block may be signaled by one or more motionvectors (MV) that may indicate the amount and/or the direction of motionbetween the current block and one or more of its reference blocks.

If multiple reference pictures are supported (e.g., as may be the casefor H.264/AVC and HEVC), then for each video block its reference pictureindex may be sent. The reference index may be used to identify fromwhich reference picture in the reference picture store 164 the temporalprediction signal comes. After spatial and/or temporal prediction, themode decision and encoder controller 180 in the encoder may choose theprediction mode. The prediction mode may be selected, for example, basedon a rate-distortion optimization implementation. The prediction blockmay be subtracted from the current video block at adder 116. Theprediction residual may be transformed by transformation unit 104 andquantized by quantization unit 106. The quantized residual coefficientsmay be inverse quantized at inverse quantization unit 110 and inversetransformed at inverse transformation unit 112 to form the reconstructedresidual. The reconstructed block may be added back to the predictionblock at adder 126 to form the reconstructed video block. Furtherin-loop filtering, such as but not limited to, a deblocking filterand/or adaptive loop filter 166, may be applied on the reconstructedvideo block before it is put in the reference picture store 164 and/orused to code future video blocks. To form the output video bitstream120, coding mode (e.g., inter or intra) information, prediction modeinformation, motion information, and/or quantized residual coefficientsmay be sent to the entropy coding unit 108 to be compressed and packedto form the bitstream 120. For example, the implementations describedherein may be implemented, at least partially, within the spatialprediction unit 160.

FIG. 2 is a block diagram illustrating an example of a block-based videodecoder 200. The video bitstream 202 may be unpacked and entropy decodedat entropy decoding unit 208. The coding mode and prediction informationmay be sent to the spatial prediction unit 260 (e.g., if intra coded) orthe temporal prediction unit 262 (e.g., if inter coded) to form theprediction block. The residual transform coefficients may be sent toinverse quantization unit 210 and inverse transform unit 212 toreconstruct the residual block. The prediction block and the residualblock may be added together at 226. The reconstructed block may gothrough in-loop filtering unit 266 before it is stored in referencepicture store 264. For example, the reconstructed video 220 may be sentout to drive a display device and/or used to predict future videoblocks.

The implementations described herein may be applicable to spatialprediction units 160 and 260. The spatial prediction implementations(e.g., units) described herein may be used in conjunction with videocoding standards (e.g., H.264/AVC, HEVC, etc.). The terms “spatialprediction” and “intra prediction” may be used interchangeably herein.

Spatial prediction may be performed on video blocks or regions ofvarious sizes and shapes. For example, block sizes of 4×4, 8×8, and16×16 pixels for spatial prediction of the luma component of the videosignal may be utilized (e.g., as in H.264/AVC), and block size of 8×8pixels for the chroma components of the video signal may be utilized(e.g., as in H.264/AVC). For a luma block of size 4×4 or 8×8, a total ofnine prediction modes may be supported (e.g., 8 directional predictionmodes and the DC mode). The eight prediction directions that may besupported (e.g., in H.264/AVC) are illustrated in FIG. 3 . FIG. 3 is adiagram illustrating an example of prediction modes that may besupported. For luma block of size 16×16, a total of 4 prediction modesmay be supported (e.g., horizontal prediction mode, vertical predictionmode, DC prediction mode, and planar prediction mode). FIG. 4 is adiagram illustrating an example of horizontal prediction for a 4×4block. In FIG. 4 , the reconstructed pixels 402 (P0, P1, P2 and P3) maybe used to predict the pixels 404 in the 4×4 video block. Prediction maybe performed according to Equation (1):

L(x,0)=P0

L(x,1)=P1

L(x,2)=P2

L(x,3)=P3  Equation (1)

-   -   where L(x,y) may be the pixel to be predicted at (x,y), x,y=0 .        . . 3.

Spatial prediction using larger block sizes may be supported (e.g., inHEVC test model HM3.0). For example, spatial prediction may be performedon square block sizes of 4×4, 8×8, 16×16, 32×32, or 64×64. Additionalintra prediction modes may be supported, for example, up to 33directional intra prediction modes, together with the DC prediction modeand the planar prediction mode may be supported. FIG. 5 is a diagramillustrating an example of 34 directional intra prediction modes(including the DC prediction mode and the planar prediction mode)(e.g.,in HM3.0). Table 1 illustrates an example of a number of predictiondirections that may be supported for each block size (e.g., in HM3.0).Directional intra prediction may be performed (e.g., in HEVC) with1/32-pixel precision.

TABLE 1 Intra block size Prediction Directions 4 × 4 16 8 × 8 33 16 × 1633 32 × 32 33 64 × 64 2

Non-directional intra prediction modes may also be supported (e.g., inH.264/AVC and HEVC). For example, the DC prediction mode and the planarprediction mode may be supported. For the DC mode, the prediction valuemay be obtained by averaging the available neighboring pixels andapplying the average value to the entire block uniformly. For the planarmode, 16×16 luma blocks and chroma blocks may be utilized (e.g.,H.264/AVC), or a plurality of block sizes may be utilized (e.g. HEVCHM3.0). The planar mode (e.g., in HEVC HM3.0) may use linearinterpolation to predict smooth regions with slow transitions. FIG. 6 isa diagram illustrating an example of a non-directional intra predictionmode. As shown in FIG. 6 , the planar mode (e.g., in HM3.0) may beperformed by the following implementation:

-   -   1. The rightmost pixel 602 in the top row (e.g., marked by T)        may be replicated to predict pixels in the rightmost column;    -   2. The bottom pixel 604 in the left column (e.g., marked by L)        may be replicated to predict pixels in the bottom row;    -   3. Bilinear interpolation in the horizontal direction (e.g.,        block 606) may be performed to produce a first prediction H(x,y)        of center pixels;    -   4. Bilinear interpolation in the vertical direction (e.g., block        608) may be performed to produce a second prediction V(x,y) of        center pixels; and    -   5. An additional averaging between the horizontal prediction and        the vertical prediction may be performed to obtain the final        prediction L(x,y), using for example,        L(x,y)=((H(x,y)+V(x,y))>>1).

Using a block-based intra prediction implementation, the entire blockmay be predicted from reconstructed neighboring pixels to the leftand/or to the top of the current block. For the pixels located towardthe right and bottom portion of the block, the distance between thepixels and pixels that may be used for prediction may increase. Forexample, as the distance increases between the prediction pixels and thepixels being predicted, the correlation between these pixels maydecrease and the prediction accuracy may decrease. This decrease inaccuracy may be further aggravated for larger block sizes (e.g., forHEVC which supports intra prediction using larger block sizes (e.g.,16×16 and above)).

Implementations (e.g., line-based intra coding) may address issuesrelated to the reduced prediction accuracy when pixel distanceincreases. Instead of applying prediction to the whole block from thetop and left neighbors, line based prediction implementations maypredict the block one line at a time. As each line gets predicted andreconstructed, it may be used to predict the next line. A line-basedintra prediction implementation may be performed either row-by-row orcolumn-by-column. A line-based intra coding implementation may beincorporated into an implementation referred to as Short Distance IntraPrediction or SDIP. A SDIP implementation may partition each squareblock of size N×N (e.g., N×N may be anywhere between 4×4 and 64×64) intoa combination of rectangle blocks of size M×K. When either M or K isequal to 1, SDIP may become equivalent to line-based intra prediction.Pixels may be predicted and reconstructed rectangle-by-rectangle. FIG. 7is a diagram illustrating an example of SDIP on a 32×32 block. The 32×32block may be partitioned into four 16×16 blocks. Looking at thebottom-left 16×16 block, for example, it may be partitioned into four4×16 rectangular blocks. The left most 4×16 block may be furtherpartitioned into four 1×16 vertical lines, and then predicted andreconstructed line-by-line. The remaining three 4×16 rectangular blocksmay be predicted and reconstructed rectangle-by-rectangle. SDIP mayprovide flexible ways to partition a video block. The video encoder maysearch through different combinations to find the optimal partitioningmode.

Line-based intra prediction and SDIP may shorten the distance betweenthe prediction pixels and those being predicted. Line-based intraprediction and SDIP may increase computational complexity andimplementation complexity, for example, at the encoder side and/or atthe decoder side. To support various rectangular block sizes, transform,quantization, residual coefficient scanning, and entropy coding may bechanged. The encoder may search through many additional modes, forexample, as described herein.

Implementations described herein may relate intra prediction techniqueswhich may be referred to as Mode-Dependent Subsampling Intra Prediction(MDS-IP). MDS-IP may alleviate or reduce the reduction in predictionaccuracy as pixel distance increases. Transform, quantization,coefficient scanning, and entropy coding processes may be modifiedslightly when implementing MDS-IP. The encoder may not consider anyadditional modes when choosing an optimal prediction mode, or theencoder may consider one or more additional modes when choosing theoptimal prediction mode.

The term “video block” may be used herein as an expansive general term.The implementations described herein may be applied to a variety ofvideo blocks, such as, but not limited to blocks of a luma component andblocks of a chroma component. The terms “samples” and “pixels” may beused interchangeably. The terms “subsampled blocks” and “subblocks” maybe used interchangeably.

FIG. 8 is a block diagram illustrating an example of an encoder 800implementing MDS-IP. The MDS-IP encoder block diagram may beincorporated into an encoder, for example, an encoder similar to theencoder 100 exemplified in FIG. 1 (e.g., at the spatial prediction block160). The encoder (e.g., via a processor) may receive a video streamcomprising one or more video blocks. The encoder may perform subsamplingon a video block, which may partition the video block into a firstsubsampled block 810 and one or more remaining subsampled blocks 826.For example, after receiving a prediction mode and based on theprediction mode (e.g., one of the prediction modes described herein), aspecific subsampling implementation may be performed by themode-dependent subsampling unit 840. The prediction mode may bedetermined, for example, by a mode decision and encoder controller(e.g., the mode decision and encoder controller 180 of FIG. 1 ). As aresult of subsampling, a portion (e.g., one half or one quarter) of theinput video block may be retained as the subsampled block 810. Thesubsampled block 810 may be referred to as a first sub block. The otherportion of the block (e.g., the portion of the block “removed” duringsubsampling) may be referred to as the remaining sub blocks 826 (e.g.,as illustrated in FIG. 8 ). The remaining sub blocks 826 may comprisemissing pixels.

The subsampling implementation may be a decimation process. Thesubsampling implementation may be a relatively more sophisticatedprocess involving downsampling filters. A predicted subsampled block 812may be determined (e.g., generated) by the intra prediction unit 842based on the prediction mode. The intra prediction unit 842 may receiveneighboring pixels, for example, such as those described herein (e.g.,with reference to FIGS. 9-17 ). The prediction mode may be, for example,any of the directional or non-directional intra prediction modes, asdescribed herein. For example, the directional prediction mode may be avertical prediction mode, a horizontal prediction mode, a diagonalprediction mode, or a non-diagonal prediction mode. For example, thenon-directional prediction mode may be a DC prediction mode or a planarprediction mode. The predicted subsampled block 812 may be subtractedfrom the subsampled block 810 by adder 820 to get the subsampled blockresidual 822. The subsampled block residual 822 may be transformed andquantized at transformation and quantization block 832. Thetransformation and quantization block 832 may generate a block ofcoefficients that are associated with the subsampled block 810. Thesubsampled block residual 822 (e.g., the block of coefficients that areassociated with the subsampled block 810) may be inverse quantized andinverse transformed at inverse quantization and inverse transformationblock 834 to obtain the reconstructed subsampled block residual 824. Thereconstructed subsampled block residual 824 may be added to thepredicted subsampled block 812 at adder 848 to form a reconstructedsubsampled block 814.

For example, the transformation and quantization block 832 may use a set(e.g., a first set) of transformation and quantization parameters. Theset of transformation and quantization parameters used by thetransformation and quantization block 832 may be based on a non-squareshaped transform. The non-square shaped transformed may comprise aplurality of square-shaped transforms. The set of transformation andquantization parameters used by the transformation and quantizationblock 832 may be associated with a shape-adaptive discrete cosinetransformation.

For example, the inverse quantization and inverse transformation block834 may use a set (e.g. a first set) of inverse quantization and inversetransformation parameters. The set of inverse quantization and inversetransformation parameters used by the inverse quantization and inversetransformation block 834 may be based on a non-square shaped transform.The non-square shaped transformed may comprise a plurality ofsquare-shaped transforms. The set of inverse quantization and inversetransformation parameters used by the inverse quantization and inversetransformation block 834 may be associated with a shape-adaptivediscrete cosine transformation.

The reconstructed subsampled block 814 may be interpolated by themode-dependent interpolation unit 844 to generate a prediction for theone or more subsampled blocks 816 comprising missing samples, which maybe based on the prediction mode. The specific interpolation processperformed by the mode-dependent interpolation unit 844 may bemode-dependent. For example, the specific interpolation processperformed by the mode-dependent interpolation unit 844 may be thereverse process of the mode dependent subsampling process utilized bymode-dependent subsampling unit 840. The prediction accuracy of the oneor more subsampled blocks 816 comprising the missing samples may berelatively increased since the distance between the prediction pixelsand those to be predicted may be reduced (e.g., may be significantlyreduced).

Still referring to FIG. 8 , the prediction residual corresponding to theone or more subsampled blocks 816 comprising the missing samples may betransformed and quantized at transformation and quantization block 836.The transformation and quantization block 836 may generate a block ofcoefficients that are associated with the remaining sub blocks 826. Theprediction residual corresponding to the one or more subsampled blocks816 comprising the missing samples (e.g., the block of coefficients thatare associated with the remaining sub blocks 826) may be inversequantization and inverse transformation at inverse quantization andinverse transformation block 838. The reconstructed residual may beadded back to the predicted one or more subsampled block(s) comprisingthe missing samples 816 to form the reconstructed one or more subsampledblocks comprising the missing samples 818. The reconstructed subsampledblock 814 and the reconstructed one or more subsampled blocks comprisingthe missing samples 818 may form the coded representation of the inputvideo block (e.g., a reconstructed video block). The formation of thecoded representation of the input video block may be based on theprediction mode.

For example, the transformation and quantization block 836 may use a set(e.g., a second set) of transformation and quantization parameters. Theset of transformation and quantization parameters used by thetransformation and quantization block 836 may be based on a non-squareshaped transform. The non-square shaped transformed may comprise aplurality of square-shaped transforms. The set of transformation andquantization parameters used by the transformation and quantizationblock 836 may be associated with a shape-adaptive discrete cosinetransformation.

For example, the inverse quantization and inverse transformation block838 may use a set (e.g. a second set) of inverse quantization andinverse transformation parameters. The set of inverse quantization andinverse transformation parameters used by the inverse quantization andinverse transformation block 838 may be based on a non-square shapedtransform. The non-square shaped transformed may comprise a plurality ofsquare-shaped transforms. The set of inverse quantization and inversetransformation parameters used by the inverse quantization and inversetransformation block 838 may be associated with a shape-adaptivediscrete cosine transformation.

The transformation and quantization block 836 may or may not use thesame parameters as the parameters used by the transformation andquantization block 832 (e.g., the second set of transformation andquantization parameters may be the same as or may be different from thefirst set of transformation and quantization parameters). The inversequantization and inverse transformation block 838 may or may not use thesame parameters as the parameters used by the inverse quantization andinverse transformation block 834 (e.g., the second set of inversequantization and inverse transformation parameters may be the same as ormay be different from the first set of inverse quantization and inversetransformation parameters).

Using the subsampled block 810 to predict the one or more subsampledblocks 816 comprising the missing samples may improve predictionaccuracy by reducing the distance between the prediction pixels andthose to be predicted. Better prediction accuracy may result in reducedprediction residual energy, which in turn may result in a significantreduction in the number of bits used to code such residual signals. Whensubsampling is performed by a factor of two in the horizontal dimensionand/or in the vertical dimension, the resulting subsampled block sizesmay be regular. For example, if the input video block is of size 2N×2N,then the subsampled block size may be 2N×N, N×2N or N×N. To processsubsampled blocks of size 2N×N or N×2N, for example, the blocktransforms and coefficient scanning orders designed for a square blockmay be applied without further change. For example, for a subsampledblock of size 2N×N or N×2N, the subsampled block may be processed byapplying two (2) N×N transforms, followed by the coefficient scanningorder designed for square blocks. Modifications to block transforms andcoefficient scanning order to support 2N×N or N×2N block sizes may beapplied for improved coding efficiency.

Subsampling may be performed in more than one direction. The subsamplingrates may be the same or may be different for each of the directions.For example, subsampling may be performed in a first direction at afirst subsampling rate and in a second dimension at a second subsamplingrate. The first subsampling rate may be the same as or different fromthe second subsampling rate.

For the one or more subsampled blocks comprising the missing samples816, for example, the transform and quantization unit 836 and theinverse quantization and inverse transform unit 838 may be skipped(e.g., the prediction residual may not be coded), as the predictionprocess using mode-dependent interpolation unit 844 may be sufficientlyaccurate that residual coding may be by-passed. The transform andquantization unit 836 and the inverse transform and inverse quantizationunit 838 may be split into two or more steps and may be performed in acascaded manner, for example, as described herein.

The decision regarding whether to perform the MDS-IP implementation maybe decided prior to encoding. For example, MDS-IP may be performed forblocks of certain sizes and certain prediction modes. No additionalsignaling in the bitstream may be required. The selection may be decided“on-the-fly” by the encoder, for example, based on one or moreparameters, such as, but not limited to rate-distortion optimizationconsiderations. An additional syntax element may be signaled in thebitstream (e.g., bitstream 120) to convey to the decoder whichimplementation (e.g., MDS-IP) may be used. The decision may be based on,for example, the size of the block. Different blocks may be more or lessprone to distance induced prediction accuracy issues depending on theirsizes.

Although an encoder is described with reference to FIG. 8 , a decoderimplementing MDS-IP may comprise one or more of the elements describedwith reference to FIG. 8 and/or may perform similar implementations(e.g., inverse implementations) to decode an encoded video stream. AnMDS-IP decoder block diagram may be incorporated into a decoder, forexample, a decoder similar to the decoder 200 exemplified in FIG. 2(e.g., at the spatial prediction block 260). For example, althoughtransformation and quantization and inverse quantization and inversetransformation may be performed on the sub block 810 and the remainingsub blocks 826 by the encoder, the decoder may perform inversequantization and inverse transformation but not perform transformationand quantization when reconstructing the video block from the one ormore blocks of coefficients associated with the first sub block 810 andthe remaining sub blocks 826.

FIG. 20 is a block diagram illustrating an example of a decoderimplementing Mode-Dependent Subsampling Intra Prediction (MDS-IP). AMDS-IP decoder 2000 may be incorporated into a decoder, for example, adecoder similar to the decoder 200 exemplified in FIG. 2 (e.g., at thespatial prediction block 260). The MDS-IP decoder 2000 (e.g., via aprocessor) may receive an encoded video stream. The encoded video streammay comprise one or more blocks of coefficients representing one or moreencoded video blocks. The encoded video blocks may be a luma componentor a chroma component of the encoded video stream. Each of the one ormore encoded video blocks may be partitioned into a first sub block andone or more remaining sub blocks. After receiving a block ofcoefficients 2010 associated with the first sub block, the decoder mayperform inverse quantization and inverse transformation at inversequantization and inverse transformation unit 2034 on the block ofcoefficients 2010 to generate a reconstructed residual 2024corresponding to the first sub block. After receiving one or more blocksof coefficients 2026 associated with the one or more remaining subblocks, the decoder may perform inverse quantization and inversetransformation at inverse quantization and inverse transformation unit2038 on the one or more blocks of coefficients 2026 to generate areconstructed residual corresponding to the one or more remaining subblocks 2028.

The decoder may receive an indication of a prediction mode for the videoblock and determine one or more interpolating techniques based on theprediction mode. For example, intra prediction unit 2042 may receive anindication of a prediction mode for the video block. The intraprediction unit 2042 may also receive neighboring pixels, for example,such as those described herein (e.g., with reference to FIGS. 9-17 ).The decoder may determine a predicted first sub block 2012 using intraprediction based on the prediction mode. The decoder may add thepredicted first sub block 2012 to a reconstructed residual 2024corresponding to the first sub block to generate a reconstructed firstsub block 2014. The decoder may determine the predicted sub blocks ofthe one or more remaining sub blocks 2016 based on the one or moreinterpolating techniques for the video block. The predicted sub blocksof the one or more remaining sub blocks 2016 may be determined by themode-dependent interpolation unit 2044. The one or more interpolatingtechniques may be based on the prediction mode. The decoder may add thepredicted sub blocks of the one or more remaining sub blocks 2016 to areconstructed residual corresponding to the one or more remaining subblocks 2028 to generate one or more reconstructed remaining sub blocks2018. The decoder may form a reconstructed video block based on theprediction mode, the reconstructed first sub block 2014, and the one ormore reconstructed remaining sub blocks 2018.

The reconstructed residual 2024 corresponding to the first sub block maybe generated using a set (e.g., a first set) of inverse quantization andinverse transformation parameters. The set of inverse quantization andinverse transformation parameters used to generate the reconstructedresidual 2024 corresponding to the first sub block may be associatedwith a shape-adaptive discrete cosine transformation. Inversetransforming the coefficients associated with the predicted first subblock may include a non-square shaped transform. The non-square shapedtransform may include a plurality of square-shaped transforms. Thereconstructed residual corresponding to the one or more remaining subblocks 2028 may be generated using a set (e.g., a second set) of inversequantization and inverse transformation parameters. The set of inversequantization and inverse transformation parameters used to generate thereconstructed residual corresponding to the one or more remaining subblocks 2028 may be associated with a shape-adaptive discrete cosinetransformation. The set of inverse quantization and inversetransformation parameters used to generate the reconstructed residualcorresponding to the first sub block 2024 may be the same as ordifferent from the set of inverse quantization and inversetransformation parameters used to generate the reconstructed residualcorresponding to the one or more remaining sub blocks 2028.

FIG. 9(A) is a diagram illustrating an example prediction process for an8×8 block using a horizontal mode. As illustrated by the arrows in FIG.9(A), prediction pixels 902 from already coded neighbors may bepropagated through columns 0 through 7 using equation (1) to predict the8×8 block 904. FIGS. 9(B)-9(C) are diagrams illustrating an exampleMDS-IP process for an 8×8 block. While an 8×8 block is shown, MDS-IP maybe used for blocks having a variety of sizes. In the MDS-IP process, the8×8 block may be downsampled in the horizontal direction. FIG. 9(B) andFIG. 9(C) may illustrate the 8×8 block before and after downsampling,respectively. The pixels which remain in the subblock after subsamplingmay be shaded in FIG. 9(B). As a result of the subsampling, subsampledblock 910 may comprise columns 1, 3, 5 and 7 (e.g., as shown in FIG.9(C)). A 2:1 subsampling rate may be used (e.g., as shown in FIGS.9(A)-9(D). A wide variety of subsampling rates may be used. Columns 1,3, 5 and 7 may be predicted in the horizontal direction (e.g., as may beindicated by the arrows in FIG. 9(C)) to form the predicted subsampledblock 812 (e.g., FIG. 8 ). The residual of the subsampled block may gothrough transformation, quantization, inverse transformation, andinverse quantization to form the reconstructed prediction residual 824.The reconstructed prediction residual 824 may be added to the predictedsubsampled block 812 to form the reconstructed subsampled block 814.Block transform and coefficient scanning designed for square shapedblocks may be used. For example, two 4×4 block transforms may be used tocomplete the transformation and quantization and subsequent inversequantization and inverse transformation by units 832 and 834.Modifications to the block transform and coefficient scanning order maybe made to support rectangular blocks (e.g., the 4×8 block in FIG.9(C)). For example, a 4×8 block transform and appropriate coefficientscanning may be used by units 832 and 834.

The second subsampled block of 4×8 pixels comprising the missing columns0, 2, 4 and 6 may be predicted by interpolating from the already codedneighboring column and the reconstructed pixels in columns 1, 3, 5, 7(e.g., as illustrated in FIG. 9(D)). Various interpolation filters maybe applied. For example, a bilinear filter, a 6-tap filter withcoefficients [1-5 20 20-5 1]/32, a 4-tap filter with coefficients [1 3 31]/8, and/or other interpolation filters with other tap lengths may beapplied. FIG. 9(D) may illustrate interpolation in the horizontaldirection using two neighboring pixels. More pixels may be involved inthe interpolation process (e.g., when filters of longer tap lengths areused). Performing horizontal downsampling for the horizontal predictionmode may be based on the premise that blocks that benefit from thehorizontal prediction mode may have strong pixel correlation in thehorizontal direction. Other prediction modes may utilize otherdownsampling processes. The residual of the second subsampled block maybe coded following steps 836 and 836 (e.g., FIG. 8 ), for example, usingtwo square block transforms or one rectangular block transform andappropriate coefficient scanning. If the mode dependent interpolationprovides suitable results, determining the residual of the secondsubsampled block may be by-passed (e.g., not coded).

MDS-IP implementations may be applied in a vertical mode (e.g., atransposed version of FIG. 9 ), where vertical downsampling may beperformed to retain half of the pixel rows, the first half of the pixelrows may be predicted and coded, and vertical interpolation based on thereconstructed rows may be performed to predict the second half of thepixel rows. FIG. 10 is a diagram illustrating an example vertical modedownsampling and prediction process. FIG. 10(A) is a diagramillustrating an example an 8×8 block 1002. Pixels in rows 3 and 7 may beshaded to indicate the rows of pixels that may remain after subsampling.A top row of pixels 1004 may be a row of prediction pixels. FIG. 10(B)is a diagram illustrating an example the block after downsampling, whichyields a block 1006 comprising rows 3 and 7. Pixels in these rows may bepredicted and coded. FIG. 10(C) is a diagram illustrating an example ofthe interpolation of the upsampled pixels in rows 0, 1, 2, 4, 5, and 6.These rows may be interpolated from the top row of prediction pixels andreconstructed rows 3 and 7.

Along with horizontal and vertical prediction modes, MDS-IP may beapplied to a variety of non-diagonal angular prediction modes (e.g.,prediction modes with angles between 0° and 90° and prediction modeswith angles between 90° and 180°). For example, the diagonal (e.g.,along the 45° or 135° direction) prediction modes may include thediagonal down-left mode and the diagonal down-right mode (e.g., modes 3and 4 in FIG. 3 ). Prediction modes in the diagonal direction mayinclude VER−8, VER+8 and HOR−8 (e.g., modes 3, 6, and 9 in FIG. 5 ).FIGS. 11(A)-11(D) are diagrams illustrating an example of a MDS-IPprocess on an 8×8 block that is predicted using the diagonal downrightmode. MDS-IP may be utilized for blocks of sizes other than 8×8, suchas, but not limited to larger block sizes. In FIG. 11 , the pixels inthe left column and the pixels in the top row may be the predictionpixels from already coded neighboring blocks. The remaining pixels maybe the pixels to be predicted. As shown by the diagonal arrows in FIG.11(A), the shaded prediction pixels may be propagated along the diagonaldirection.

For angular prediction modes, the block may be downsampled in bothdimensions. For example, as illustrated in FIGS. 11(B) and 11(C), an 8×8block 1102 may be downsampled by a factor of 2 in each dimension and bypixels located at (2n+1,2m+1), n,m=0 . . . 3 to form a downsampled block1104 in FIG. 11(C). These remaining pixels may be predicted in thediagonal direction, for example, as shown by the arrows in downsampledblock 1104 in FIG. 11(C). Referring to FIGS. 8, 11 (C), and 11(D), theprediction residual of the subsampled block may be coded followingprocessing by units 832 and 834 and added back to the predictedsubsampled block 812 to obtain the reconstructed subsampled block 814.Via the mode-dependent interpolation unit 844, the subsampled blockscomprising the remaining three quarters of the pixels may be predictedby interpolation from the already coded neighboring pixels and thereconstructed pixels at locations (2n+1, 2m+1), n,m=0 . . . 3. Asdescribed herein, various interpolation techniques associated with thevarious prediction modes may be used.

The subsampled blocks comprising the missing pixels may be predicted byinterpolation at the same time, for example, as illustrated by FIG.11(D). For example, the subblock comprising pixels at locations (2n,2m), n,m=0 . . . 3, may be predicted by interpolation in the diagonaldirection, for example, using the already reconstructed neighboringpixels and the reconstructed pixels at locations (2n+1, 2m+1), n,m=0 . .. 3, as shown by the arrows 1140 in FIG. 11(D). A portion (e.g., only aportion) of the arrows may be illustrated in FIG. 11(D). Interpolationalong the diagonal direction may be used due to a higher pixelcorrelation existing in that direction. Other prediction modes may usedifferent interpolation processes. The subblock comprising pixels atlocations (2n, 2m+1), n,m=0 . . . 3, may be predicted by interpolationin the horizontal direction, for example, using the alreadyreconstructed neighboring pixels and the reconstructed pixels atlocations (2n+1, 2m+1), n,m=0 . . . 3, as shown by the arrows 1142 inFIG. 11(D). The subblock comprising pixels at locations (2n+1, 2m),n,m=0 . . . 3, may be predicted by interpolation in the verticaldirection, for example, using the already reconstructed neighboringpixels and the reconstructed pixels at locations (2n+1, 2m+1), n,m=0 . .. 3, as shown by the arrows 1144 in FIG. 11(D).

Modifications may be made to the interpolation process, such as, but notlimited to different interpolation filters with different filter taplengths in the horizontal direction and/or the vertical direction may beused. After prediction, the prediction residual of the three subblockscomprising the missing pixels at locations (2n,2m), (2n,2m+1) and (2n+1,2m), respectively, may be coded following processing by units 836 and838 (e.g., FIG. 8 ), and added back to the prediction signal to obtainthe three reconstructed subblocks comprising the missing pixels 818.

FIGS. 12(A)-12(D) are diagrams illustrating examples of a diagonalprediction mode interpolation and predicting process. Referring to FIG.12 , the subblocks comprising the missing pixels may be predicted andreconstructed in a cascaded (e.g., multi-stage) manner. Referring toFIGS. 12(A) and 12(B), an input block 1202 may be downsampled in twodimensions (e.g., with a 2:1 subsampling rate in both dimensions) toyield downsampled block 1204. The pixels which remain in the block aftersubsampling may be shaded in FIG. 12(A). The pixels in block 1204 may beintra predicted using any suitable intra prediction technique, forexample, as indicated by the arrows in FIG. 12(B). As illustrated byblock 1206 in FIG. 12(C), the pixels at locations (2n, 2m), n,m=0 . . .3, may be predicted by interpolation in the diagonal direction (e.g., asshown by arrows 1220), for example, using the already reconstructedneighboring pixels and the reconstructed pixels at locations(2n+1,2m+1), n,m=0 . . . 3. The prediction residual of the subblockcomprising samples at locations (2n, 2m), n,m=0 . . . 3, may be codedfollowing the steps in 836 and 838 (e.g., FIG. 8 ). The reconstructedresidual may be added back to the prediction to obtain the reconstructedsubblock comprising pixels at locations (2n, 2m). For example, as shownby block 1208 in FIG. 12(D), the subblock comprising remaining pixels atlocations (2n, 2m+1) and the subblock comprising remaining pixels atlocations (2n+1, 2m) may be predicted by interpolation using the pixelsthat have been reconstructed, for example, using the arrows 1222 andusing the arrows 1224, respectively.

FIG. 13 is a diagram illustrating an example of an interpolationtechnique. Input block 1302 in FIG. 13(A) may be downsampled in twodirections to yield the downsampled block 1304 shown in FIG. 13(B).Various pixels may be shaded in FIG. 13(A) to show the pixels thatremain after downsampling. The pixels in downsampled block 1304 may bepredicted as indicated by the diagonal arrows in FIG. 13(B). Subsequentto reconstruction of the predicted pixels, the pixels at locations (2n,2m) and the pixels at locations (2n, 2m+1) may be predicted byinterpolation in the diagonal direction (e.g., arrows 1320) and in thehorizontal direction (e.g., arrows 1324), respectively, for example, asshown in FIG. 13(C). The prediction residuals of the subblock comprisingsamples at locations (2n,2m) and the subblock comprising samples atlocations (2n, 2m+1) may be coded following processing by units 836 and838. The reconstructed residual may be added back to obtain thereconstructed subblock comprising pixels at locations (2n, 2m) and thereconstructed subblock comprising pixels locations (2n, 2m+1),respectively. For example, as shown by block 1308 in FIG. 13(D) wherepixels at locations (2n, 2m), pixels at locations (2n, 2m+1), and pixelsat locations (2n+1, 2m+1) may have been reconstructed, the remainingsubblock comprising pixels at locations (2n+1, 2m) may be predicted inthe diagonal direction (e.g., arrows 1326), and/or the residual may becoded following processing by units 836 and 838.

If missing pixels are predicted and reconstructed in a cascaded manner,one or more of the residual coding steps (e.g., as performed by units836 and 838) may be by-passed if, for example, prediction issufficiently accurate or computational complexity is sufficiently high.Whether one or more of such steps are by-passed may be decided by theencoder and signaled to the decoder in the bitstream, for example, bysetting a coded_block_flag to 0. The encoder and the decoder may agreebeforehand which (if any) steps may be by-passed. As described herein(e.g., FIG. 12(D)), following the prediction of pixels at locations(2n+1, 2m) and locations (2n, 2m+1) using arrows 1222 and 1224, theencoder and the decoder may finish the MDS-IP process for the inputblock, and the operations in units 836 and 838 may be by-passed. Theinterpolation processes may employ interpolation filters of differentcharacteristics (e.g., different tap lengths and coefficients), such asbut not limited to a bilinear filter, a 4-tap or 6-tap 1D filters,and/or a 4×4 or 6×6 2D non-separable filters.

Although MDS-IP processing may be described herein, similar processingtechniques for other diagonal prediction modes may be performed. Forexample, both H.264/AVC and HEVC may support other directionalprediction modes. These modes, because their prediction directionfollows a finer angle, sub-pixel precision may be considered forprediction. The MDS-IP process for these prediction modes may utilizecoding of a block of pixels with non-rectangular shapes. The MDS-IPprocess for these directional prediction modes may be turned off, usingdirectional intra prediction for these modes. Transform ofnon-rectangular shapes (e.g., shape-adaptive DCT) and appropriatecoefficient scanning may be applied to the MDS-IP processing for theseprediction modes.

FIGS. 14(A)-(D) are diagrams illustrating an example of an interpolationtechnique for a non-diagonal angular prediction mode. Input block 1402in FIG. 14(A) may be downsampled in more than one direction (e.g., twodirections) to yield the downsampled block 1404 shown in FIG. 14(B).Various pixels may be shaded in FIG. 14(A) to show the pixels thatremain after downsampling. The pixels in downsampled block 1404 may bepredicted, for example, as indicated by the non-diagonal angular arrowsin FIG. 14(B). The non-diagonal angular arrows may correspond to anon-45°/non-135° angular diagonal prediction mode. While a 4:1subsampling rate (e.g., 2:1 in two directions) may be illustrated inFIG. 14 , other subsampling rates may be used. For example, a 2:1subsampling rate, a 6:1 subsampling rate, an 8:1 subsampling rate, or avariety of other suitable subsampling rates may be used. As illustratedby block 1406 in FIG. 14(C), the pixels at locations (2n, 2m), n,m=0 . .. 3 may be predicted by interpolation in the angular direction (e.g., asshown by arrows 1420) using the already reconstructed neighboring pixelsat locations (2n−1, 2m−3) and the reconstructed pixels at locations(2n+1, 2m+3). The prediction residual of the subblock comprising samplesat locations (2n, 2m), n,m=0 . . . 3, may be coded following the stepsin 836 and 838 (e.g., FIG. 8 ). The reconstructed residual may be addedback to the prediction to obtain the reconstructed subblock comprisingpixels at locations (2n, 2m). As shown by block 1408 in FIG. 14(D), thesubblock comprising the remaining pixels may be predicted byinterpolation using the pixels that have been reconstructed (e.g., atlocations (2n−1, 2m−2) and (2n+1, 2m+2), as indicated by arrows 1426).

FIGS. 15(A)-(C) are diagrams illustrating an example of an MDS-IPprocess on an 8×8 block that is predicted using a non-diagonal angularprediction mode (e.g., non-45°/non-135°). A pixel weighting process mayassist with the interpolation. While an 8×8 block may be shown in FIGS.15(A)-(C), MDS-IP may be utilized for blocks having a variety of sizes.In FIG. 15 , the pixels in the left column and the pixels in the top rowmay be the prediction pixels from already coded neighboring blocks. Theblock 1502 may be downsampled in both dimensions. For example, asillustrated in FIGS. 15(A) and 15(B), an 8×8 block 1502 may bedownsampled by a factor of 2 in each dimension and pixels located atlocations (2n+1,2m+1), n,m=0 . . . 3, may form a downsampled block 1504in FIG. 15(B). These remaining pixels may be predicted in a non-diagonalangular direction, for example, as shown by the arrows in downsampledblock 1504 in FIG. 15(B). Referring to FIGS. 8, 15 (B), and 15(C), theprediction residual of the subsampled block may be coded followingprocessing by units 832 and 834 and added back to the predictedsubsampled block 812 to obtain the reconstructed subsampled block 814.Via the mode-dependent interpolation unit 844, the subsampled blockscomprising the remaining three quarters of the pixels may be predictedby interpolation from the reconstructed subsampled block 814. Thesubsampled blocks comprising the missing pixels may be predicted byinterpolation at the same time using a weighting implementation, forexample, as illustrated by FIG. 15(C). For example, the subblockcomprising pixels at locations (2n, 2m), n,m=0 . . . 3, may be predictedby interpolation in the diagonal direction using the alreadyreconstructed neighboring pixels and the reconstructed pixels atlocations (2n+1, 2m+1), n,m=0 . . . 3, for example, as shown by block1506 and arrows 1540. The interpolation process may weigh pixelsdifferently. For example, the interpolation process may weigh the “upperleft” pixel heavier than the “lower right” pixel. The particularweighting implementation may depend on the prediction mode utilized. Forexample, the “upper left” pixel may be given a 70% weighting factorwhile the “lower right” pixel may be given a weighting factor of 30%.The subblock comprising pixels at locations (2n,2m+1), n,m=0 . . . 3,may be predicted by interpolation in the horizontal direction, using thealready reconstructed neighboring pixels and the reconstructed pixels atlocations (2n+1, 2m+1), n,m=0 . . . 3, for example, as shown by arrows1542 in FIG. 15(C). The “left” pixel and the “right” pixel may be givenequal or different weighting factors. For example, the “left” pixel maybe given a weighting of 55% while the “right” pixel may be given aweighting of 45%. The subblock comprising pixels at locations (2n+1,2m), n,m=0 . . . 3, may be predicted by interpolation in the verticaldirection using the already reconstructed neighboring pixels and thereconstructed pixels at locations (2n+1, 2m+1), n,m=0 . . . 3, forexample, as shown by the arrows 1544 in FIG. 15(C). The “top” pixel andthe “bottom” pixel may be given equal or different weighting factors.For example, the “top” pixel may be given a weighting of 60% while the“right” pixel may be given a weighting of 40%.

Modifications may be made to the interpolation process, such as, but notlimited to, different weighting factors based on the prediction mode.After prediction, the prediction residual of the three subblockscomprising the missing pixels at locations (2n, 2m), (2n, 2m+1) and(2n+1, 2m), respectively, may be coded following processing by units 836and 838 (FIG. 8 ), and may be added back to the prediction signal toobtain the three reconstructed subblocks comprising the missing pixels818. The residual coding process for the missing pixels at locations(2n,2m), (2n,2m+1) and (2n+1, 2m) may be by-passed by the encoder and/orthe decoder.

While exemplary interpolation techniques have been illustrated forhorizontal, vertical, diagonal, and non-diagonal angular predictionmodes, the MDS-IP implementations described herein may be used with avariety of video encoding and decoding prediction modes. The sameinterpolation technique or different interpolation techniques may beapplied to the one or more sub blocks. The interpolation technique(s)may include one or more filters, which may be selected based on theprediction mode. For example, the interpolation filter may be a 4-tapone-dimensional filter, a 6-tap one-dimensional filter, a 4×4two-dimensional filter, a 6×6 two-dimensional filter, among others. Oneor more interpolation filters may be applied along with one or moreinterpolation directions, which may be based on the prediction mode.

Non-directional prediction modes such as, but not limited to the DC modeand the planar prediction mode may be supported. The DC prediction maybe performed by taking the average of the prediction pixels from alreadyreconstructed neighboring blocks (e.g., the leftmost column and topcolumn in FIG. 16(A), denoted as “A”) and assigning the average value tothe entire block to be predicted (e.g., an 8×8 block 1602 in FIG.16(A)). The planar mode (e.g., as in HEVC HM3.0) may be describedherein, for example, with reference to FIG. 6 . Non-directionalprediction modes may be suitable for flat areas or areas withslow/smooth gradients. FIGS. 16(A)-(D) and 17(A)-(D) are diagramsillustrating examples of MDS-IP processing applied on an 8×8 blockpredicted using a DC prediction mode. While an 8×8 block may be shown,MDS-IP may be used to process larger blocks. The block 1602 in FIG.16(A) illustrates an example of a DC prediction implementation. FIGS.16(B)-(D) illustrate examples of processing techniques according toimplementations described herein.

For example, as shown in FIG. 16(B)-(C), the 8×8 block 1604 may bedownsampled by a factor of 2 in each dimension to generate a 4×4 block1606. Pixels located at locations (2n+1,2m+1), n,m=0 . . . 3, may bepredicted by taking the average of the prediction pixels from alreadyreconstructed neighboring blocks (e.g., the leftmost column and topcolumn in FIG. 16(C)). The prediction residual of the subsampled block822 (e.g., FIG. 8 ) may be coded following the processing by units 832and 834 and may be added back to the predicted subsampled block 812 toobtain the reconstructed subsampled block 814. The subblocks comprisingthe remaining three quarters of the pixels may be predicted byinterpolation from the already coded neighboring pixels and thereconstructed pixels at locations (2n+1, 2m+1), n,m=0 . . . 3.

Referring to FIG. 16(D), the missing pixels may be predicted byinterpolation at the same time. For example, the subblock comprisingpixels at locations (2n, 2m), n,m=0 . . . 3, may be predicted byinterpolation using the already reconstructed neighboring pixels and thereconstructed pixels at locations (2n+1, 2m+1), n,m=0 . . . 3, (e.g.from the first step of MDS-IP) for example, as shown by arrows 1620. Aportion of the arrows 1620 may be shown in FIG. 16(C). Interpolationindicated by the arrows 1620 may not possess any directionality (e.g.,due to the non-directional prediction mode). An averaging of the fourpixels may be sufficient. The subblock comprising pixels at locations(2n,2m+1), n,m=0 . . . 3, may predicted by interpolation in thehorizontal direction, for example, using the already reconstructedneighboring pixels and the reconstructed pixels at locations (2n+1,2m+1), n,m=0 . . . 3, as shown by arrows 1622 in FIG. 16(C). Thesubblock comprising pixels at locations (2n+1, 2m), n,m=0 . . . 3 may bepredicted by interpolation in the vertical direction using the alreadyreconstructed neighboring pixels and the reconstructed pixels atlocations (2n+1, 2m+1), n,m=0 . . . 3, for example, as shown by arrows1624 in FIG. 16(C).

Modifications may be made to the interpolation process, such as but notlimited to using different interpolation filters with different filtertap lengths in the horizontal direction and/or the vertical direction.After prediction, the prediction residual of the subblocks comprisingthe missing pixels may be coded following the processing by units 836and 838 and added back to the prediction of the subblocks comprising themissing pixels to obtain the reconstructed subblocks comprising themissing pixels 818.

FIGS. 17A-D are diagrams illustrating an example of an interpolationimplementation. Input block 1702 may be downsampled in two directions toyield downsampled block 1704 (e.g., which may be similar to block 1606in FIG. 16(C)). The subblocks comprising the missing pixels may bepredicted and reconstructed in a cascaded (e.g., multi-stage) manner. Asindicated by arrows 1720 in FIG. 17(C), the pixels at locations (2n,2m), n,m=0 . . . 3, may be predicted by interpolation (e.g., usingsimple averaging) using the already reconstructed neighboring pixels andthe reconstructed pixels at locations (2n+1,2m+1), n,m=0 . . . 3. Theprediction residual of the subblock comprising samples at locations (2n,2m), n,m=0 . . . 3, may be coded following processing by units 836 and838. The reconstructed residual may be added back to the prediction toobtain the reconstructed subblock comprising pixels at locations (2n,2m). As shown in FIG. 17(D), the subblock comprising the remainingpixels at locations (2n, 2m+1) and the subblock comprising the remainingpixels at locations (2n+1, 2m) may be predicted by interpolation usingpixels that may have been reconstructed, for example, using arrows 1722and using arrows 1724, respectively.

The interpolation processes in FIG. 16(C), FIG. 17(C), and FIG. 17(D)may employ interpolation filters of different characteristics (e.g.,different tap lengths and coefficients), such as but not limited to abilinear filter (e.g., simple averaging), 4-tap or 6-tap 1D filters,and/or 4×4 or 6×6 2D non-separable filters. Although MDS-IPimplementations may be described herein using the DC prediction mode asan example, MDS-IP implementations for other non-directional predictionmodes (e.g., the planar prediction mode) may be substantially similar.

MDS-IP may be applicable to a wide variety of prediction modes. Whilethe specific MDS-IP implementations for different prediction modes mayvary, they may generally comprise a two-step procedure. For example, ina first step, a subsampled block comprising a portion (e.g., a half or aquarter) of the pixels in the input video block may be generated byapplying a mode-dependent subsampling process. The subsampled block maybe predicted based on the prediction mode and the prediction residual ofthe subsampled block may be computed and coded to obtain thereconstructed residual. The reconstructed subsampled block may then begenerated. For example, in a second step, the one or more subblockscomprising the remaining pixels in the input video block may bepredicted by interpolating from already coded neighboring pixels and thereconstructed subsampled block previously generated. The specificinterpolation process (e.g., interpolation filter, interpolationdirection, etc.) may depend on the prediction mode. The predictionresidual of the one or more subblocks comprising the remaining pixels inthe input video block may be coded.

As described herein, the sub blocks comprising the missing pixels may bepredicted and reconstructed in a cascaded (e.g., multi-stage) manner.For example, the pixels at a first location (e.g., locations (2n, 2m)with reference to FIG. 12 ) may be referred to as a first portion ofreconstructed subblocks. The pixels at a second location (e.g., atlocations (2n, 2m+1) and/or at locations (2n+1, 2m) with reference toFIG. 12 ) may be referred to as a second portion of reconstructedsubblocks. A second portion of reconstructed subblocks may be generatedbased at least partially on a generated first portion of reconstructedsubblocks (e.g., as shown in FIG. 12(D), FIG. 13(D), FIG. 14(D), etc.).The transformation and quantization parameters (e.g., a third set) usedto generate the second portion of reconstructed subblocks may be thesame as the set of transformation and quantization parameters used togenerate the reconstructed residual of the subblock (e.g., the firstset) or the transformation and quantization parameters used to generatethe first portion of reconstructed subblocks (e.g., the second set).

Implementations may utilize various approaches for achieving the desiredresults. For example, one or more of the subsampled blocks (e.g.,generated during the first and/or the second step of MDS-IP) may not beof square shape. 2D transform designed for the non-square shapedsubsampled blocks, as well as appropriate coefficient scanning orders,may be designed and applied. Square-shaped 2D transform, as well asscanning order, may be applied to the non-square rectangular shapedsubblocks.

The residual coding process in the first step of MDS-IP (e.g., units 832and 834) and the residual coding process in the second step of MDS-IP(e.g., units 836 and 838) may or may not be the same. The same transformand quantization parameters or different transform and quantizationparameters may be applied during these steps. One or more of thetransform unit 104, quantization unit 106, inverse quantization unit110, and inverse transform unit 112 (e.g., as shown in FIG. 1 ) may beused by the MDS-IP processing.

The mode-dependent interpolation process (e.g., as performed bymode-dependent interpolation unit 844) may generate a prediction signalfor the one or more subsampled blocks comprising the missing samples,followed by the residual for the one or more subsampled blockscomprising the missing samples being reconstructed. Prediction andresidual generation may be performed in a cascaded manner, for example,where a first portion of the one or more subblocks comprising themissing samples may be coded first, and then may be used to predict andcode the second portion of the one or more subblocks comprising themissing samples.

The prediction residuals generated during the first step of the MDS-IPprocessing and the second step of the MDS-IP processing may be coded. Atleast some of the prediction residuals generated during the second stepof MDS-IP may not be coded.

FIG. 18 is a diagram illustrating an example of a communication system1800. An encoder 1802 may be in communication with a communicationsnetwork 1804 via a connection 1808. The encoder 1802 may utilize theMDS-IP processing as described herein. The connection 1808 may be awireline connection or a wireless connection. A decoder 1806 may be incommunication with the communications network 1806 via a connection1810. The encoder 1806 may utilize the MDS-IP processing as describedherein. The connection 1810 may be a wireline connection or a wirelessconnection. The communications network 1806 may be a suitable type ofcommunication system, for example, as described herein. The encoder 1806may be incorporated into any of a wide variety of terminals, such as,but not limited to, digital televisions, wireless communication devices,wireless broadcast systems, personal digital assistants (PDAs), laptopor desktop computers, tablet computers, digital cameras, digitalrecording devices, video gaming devices, video game consoles, cellularor satellite radio telephones, digital media players, and the like.

FIG. 19A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 1900 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 1900 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems1900 may employ one or more channel access methods, such as codedivision multiple access (CDMA), time division multiple access (TDMA),frequency division multiple access (FDMA), orthogonal FDMA (OFDMA),single-carrier FDMA (SC-FDMA), and the like.

As shown in FIG. 19A, the communications system 1900 may includewireless transmit/receive units (WTRUs) 1902 a, 1902 b, 1902 c, 1902 d,a radio access network (RAN) 1903/1904/1905, a core network1906/1907/1909, a public switched telephone network (PSTN) 1908, theInternet 1910, and other networks 1912, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 1902 a,1902 b, 1902 c, 1902 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 1902 a, 1902 b, 1902 c, 1902 d may be configured to transmitand/or receive wireless signals and may include user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a smartphone, a laptop, anetbook, a personal computer, a wireless sensor, consumer electronics,or any other terminal capable of receiving and processing compressedvideo communications.

The communications systems 1900 may also include a base station 1914 aand a base station 1914 b. Each of the base stations 1914 a, 1914 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 1902 a, 1902 b, 1902 c, 1902 d to facilitate access toone or more communication networks, such as the core network1906/1907/1909, the Internet 1910, and/or the networks 1912. By way ofexample, the base stations 1914 a, 1914 b may be a base transceiverstation (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, asite controller, an access point (AP), a wireless router, and the like.While the base stations 1914 a, 1914 b are each depicted as a singleelement, it will be appreciated that the base stations 1914 a, 1914 bmay include any number of interconnected base stations and/or networkelements.

The base station 1914 a may be part of the RAN 1903/1904/1905, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 1914 a and/or the base station1914 b may be configured to transmit and/or receive wireless signalswithin a particular geographic region, which may be referred to as acell (not shown). The cell may further be divided into cell sectors. Forexample, the cell associated with the base station 1914 a may be dividedinto three sectors. Thus, in one embodiment, the base station 1914 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 1914 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 1914 a, 1914 b may communicate with one or more of theWTRUs 1902 a, 1902 b, 1902 c, 1902 d over an air interface1915/1916/1917, which may be any suitable wireless communication link(e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV),visible light, etc.). The air interface 1915/1916/1917 may beestablished using any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 1900 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 1914 a in the RAN 1903/1904/1905 and the WTRUs1902 a, 1902 b, 1902 c may implement a radio technology such asUniversal Mobile Telecommunications System (UMTS) Terrestrial RadioAccess (UTRA), which may establish the air interface 1915/1916/1917using wideband CDMA (WCDMA). WCDMA may include communication protocolssuch as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+).HSPA may include High-Speed Downlink Packet Access (HSDPA) and/orHigh-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 1914 a and the WTRUs 1902 a,1902 b, 1902 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface1915/1916/1917 using Long Term Evolution (LTE) and/or LTE-Advanced(LTE-A).

In other embodiments, the base station 1914 a and the WTRUs 1902 a, 1902b, 1902 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 1914 b in FIG. 19A may be a wireless router, Home NodeB, Home eNode B, or access point, for example, and may utilize anysuitable RAT for facilitating wireless connectivity in a localized area,such as a place of business, a home, a vehicle, a campus, and the like.In one embodiment, the base station 1914 b and the WTRUs 1902 c, 1902 dmay implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In another embodiment, the basestation 1914 b and the WTRUs 1902 c, 1902 d may implement a radiotechnology such as IEEE 802.15 to establish a wireless personal areanetwork (WPAN). In yet another embodiment, the base station 1914 b andthe WTRUs 1902 c, 1902 d may utilize a cellular-based RAT (e.g., WCDMA,CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell.As shown in FIG. 19A, the base station 1914 b may have a directconnection to the Internet 1910. Thus, the base station 1914 b may notbe required to access the Internet 1910 via the core network1906/1907/1909.

The RAN 1903/1904/1905 may be in communication with the core network1906, which may be any type of network configured to provide voice,data, applications, and/or voice over internet protocol (VoIP) servicesto one or more of the WTRUs 1902 a, 1902 b, 1902 c, 1902 d. For example,the core network 1906/1907/1909 may provide call control, billingservices, mobile location-based services, pre-paid calling, Internetconnectivity, video distribution, etc., and/or perform high-levelsecurity functions, such as user authentication. Although not shown inFIG. 19A, it will be appreciated that the RAN 1903/1904/1905 and/or thecore network 1906/1907/1909 may be in direct or indirect communicationwith other RANs that employ the same RAT as the RAN 1903/1904/1905 or adifferent RAT. For example, in addition to being connected to the RAN1903/1904/1905, which may be utilizing an E-UTRA radio technology, thecore network 1906/1907/1909 may also be in communication with anotherRAN (not shown) employing a GSM radio technology.

The core network 1906/1907/1909 may also serve as a gateway for theWTRUs 1902 a, 1902 b, 1902 c, 1902 d to access the PSTN 1908, theInternet 1910, and/or other networks 1912. The PSTN 1908 may includecircuit-switched telephone networks that provide plain old telephoneservice (POTS). The Internet 1910 may include a global system ofinterconnected computer networks and devices that use commoncommunication protocols, such as the transmission control protocol(TCP), user datagram protocol (UDP) and the internet protocol (IP) inthe TCP/IP internet protocol suite. The networks 1912 may include wiredor wireless communications networks owned and/or operated by otherservice providers. For example, the networks 1912 may include anothercore network connected to one or more RANs, which may employ the sameRAT as the RAN 1903/1904/1905 or a different RAT.

Some or all of the WTRUs 1902 a, 1902 b, 1902 c, 1902 d in thecommunications system 1900 may include multi-mode capabilities, i.e.,the WTRUs 1902 a, 1902 b, 1902 c, 1902 d may include multipletransceivers for communicating with different wireless networks overdifferent wireless links. For example, the WTRU 1902 c shown in FIG. 19Amay be configured to communicate with the base station 1914 a, which mayemploy a cellular-based radio technology, and with the base station 1914b, which may employ an IEEE 802 radio technology.

FIG. 19B is a system diagram of an example WTRU 1902. As shown in FIG.19B, the WTRU 1902 may include a processor 1918, a transceiver 1920, atransmit/receive element 1922, a speaker/microphone 1924, a keypad 1926,a display/touchpad 1928, non-removable memory 1906, removable memory1932, a power source 1934, a global positioning system (GPS) chipset1936, and other peripherals 1938. It will be appreciated that the WTRU1902 may include any sub-combination of the foregoing elements whileremaining consistent with an embodiment. Also, embodiments contemplatethat the base stations 1914 a and 1914 b, and/or the nodes that basestations 1914 a and 1914 b may represent, such as but not limited totransceiver station (BTS), a Node-B, a site controller, an access point(AP), a home node-B, an evolved home node-B (eNodeB), a home evolvednode-B (HeNB), a home evolved node-B gateway, and proxy nodes, amongothers, may include some or all of the elements depicted in FIG. 1B anddescribed herein.

The processor 1918 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), agraphics processing unit (GPU), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Array (FPGAs) circuits, any other type of integratedcircuit (IC), a state machine, and the like. The processor 1918 mayperform signal coding, data processing, power control, input/outputprocessing, and/or any other functionality that enables the WTRU 1902 tooperate in a wireless environment. The processor 1918 may be coupled tothe transceiver 1920, which may be coupled to the transmit/receiveelement 1922. While FIG. 19B depicts the processor 1918 and thetransceiver 1920 as separate components, it will be appreciated that theprocessor 1918 and the transceiver 1920 may be integrated together in anelectronic package or chip.

The transmit/receive element 1922 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 1914a) over the air interface 1915/1916/1917. For example, in oneembodiment, the transmit/receive element 1922 may be an antennaconfigured to transmit and/or receive RF signals. In another embodiment,the transmit/receive element 1922 may be an emitter/detector configuredto transmit and/or receive IR, UV, or visible light signals, forexample. In yet another embodiment, the transmit/receive element 1922may be configured to transmit and receive both RF and light signals. Itwill be appreciated that the transmit/receive element 1922 may beconfigured to transmit and/or receive any combination of wirelesssignals.

In addition, although the transmit/receive element 1922 is depicted inFIG. 19B as a single element, the WTRU 1902 may include any number oftransmit/receive elements 1922. More specifically, the WTRU 1902 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 1902 mayinclude two or more transmit/receive elements 1922 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 1915/1916/1917.

The transceiver 1920 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 1922 and to demodulatethe signals that are received by the transmit/receive element 1922. Asnoted above, the WTRU 1902 may have multi-mode capabilities. Thus, thetransceiver 1920 may include multiple transceivers for enabling the WTRU1902 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 1918 of the WTRU 1902 may be coupled to, and may receiveuser input data from, the speaker/microphone 1924, the keypad 1926,and/or the display/touchpad 1928 (e.g., a liquid crystal display (LCD)display unit or organic light-emitting diode (OLED) display unit). Theprocessor 1918 may also output user data to the speaker/microphone 1924,the keypad 1926, and/or the display/touchpad 1928. In addition, theprocessor 1918 may access information from, and store data in, any typeof suitable memory, such as the non-removable memory 1906 and/or theremovable memory 1932. The non-removable memory 1906 may includerandom-access memory (RAM), read-only memory (ROM), a hard disk, or anyother type of memory storage device. The removable memory 1932 mayinclude a subscriber identity module (SIM) card, a memory stick, asecure digital (SD) memory card, and the like. In other embodiments, theprocessor 1918 may access information from, and store data in, memorythat is not physically located on the WTRU 1902, such as on a server ora home computer (not shown).

The processor 1918 may receive power from the power source 1934, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 1902. The power source 1934 may be any suitabledevice for powering the WTRU 1902. For example, the power source 1934may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 1918 may also be coupled to the GPS chipset 1936, whichmay be configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 1902. In additionto, or in lieu of, the information from the GPS chipset 1936, the WTRU1902 may receive location information over the air interface1915/1916/1917 from a base station (e.g., base stations 1914 a, 1914 b)and/or determine its location based on the timing of the signals beingreceived from two or more nearby base stations. It will be appreciatedthat the WTRU 1902 may acquire location information by way of anysuitable location-determination method while remaining consistent withan embodiment.

The processor 1918 may further be coupled to other peripherals 1938,which may include one or more software and/or hardware modules thatprovide additional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 1938 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 19C is a system diagram of the RAN 1903 and the core network 1906according to an embodiment. As noted above, the RAN 1903 may employ aUTRA radio technology to communicate with the WTRUs 1902 a, 1902 b, 1902c over the air interface 1915. The RAN 1904 may also be in communicationwith the core network 1906. As shown in FIG. 19C, the RAN 1903 mayinclude Node-Bs 1940 a, 1940 b, 1940 c, which may each include one ormore transceivers for communicating with the WTRUs 1902 a, 1902 b, 1902c over the air interface 1915. The Node-Bs 1940 a, 1940 b, 1940 c mayeach be associated with a particular cell (not shown) within the RAN1903. The RAN 1903 may also include RNCs 1942 a, 1942 b. It will beappreciated that the RAN 1903 may include any number of Node-Bs and RNCswhile remaining consistent with an embodiment.

As shown in FIG. 19C, the Node-Bs 1940 a, 1940 b may be in communicationwith the RNC 1942 a. Additionally, the Node-B 1940 c may be incommunication with the RNC 1942 b. The Node-Bs 1940 a, 1940 b, 1940 cmay communicate with the respective RNCs 1942 a, 1942 b via an Iubinterface. The RNCs 1942 a, 1942 b may be in communication with oneanother via an Iur interface. Each of the RNCs 1942 a, 1942 b may beconfigured to control the respective Node-Bs 1940 a, 1940 b, 1940 c towhich it is connected. In addition, each of the RNCs 1942 a, 1942 b maybe configured to carry out or support other functionality, such as outerloop power control, load control, admission control, packet scheduling,handover control, macrodiversity, security functions, data encryption,and the like.

The core network 1906 shown in FIG. 19C may include a media gateway(MGW) 1944, a mobile switching center (MSC) 1946, a serving GPRS supportnode (SGSN) 1948, and/or a gateway GPRS support node (GGSN) 1950. Whileeach of the foregoing elements are depicted as part of the core network1906, it will be appreciated that any one of these elements may be ownedand/or operated by an entity other than the core network operator.

The RNC 1942 a in the RAN 1903 may be connected to the MSC 1946 in thecore network 1906 via an IuCS interface. The MSC 1946 may be connectedto the MGW 1944. The MSC 1946 and the MGW 1944 may provide the WTRUs1902 a, 1902 b, 1902 c with access to circuit-switched networks, such asthe PSTN 1908, to facilitate communications between the WTRUs 1902 a,1902 b, 1902 c and traditional land-line communications devices.

The RNC 1942 a in the RAN 1903 may also be connected to the SGSN 1948 inthe core network 1906 via an IuPS interface. The SGSN 1948 may beconnected to the GGSN 1950. The SGSN 1948 and the GGSN 1950 may providethe WTRUs 1902 a, 1902 b, 1902 c with access to packet-switchednetworks, such as the Internet 1910, to facilitate communicationsbetween and the WTRUs 1902 a, 1902 b, 1902 c and IP-enabled devices.

As noted above, the core network 1906 may also be connected to thenetworks 1912, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 19D is a system diagram of the RAN 1904 and the core network 1907according to another embodiment. As noted above, the RAN 1904 may employan E-UTRA radio technology to communicate with the WTRUs 1902 a, 1902 b,1902 c over the air interface 1916. The RAN 1904 may also be incommunication with the core network 1907.

The RAN 1904 may include eNode-Bs 1960 a, 1960 b, 1960 c, though it willbe appreciated that the RAN 1904 may include any number of eNode-Bswhile remaining consistent with an embodiment. The eNode-Bs 1960 a, 1960b, 1960 c may each include one or more transceivers for communicatingwith the WTRUs 1902 a, 1902 b, 1902 c over the air interface 1916. Inone embodiment, the eNode-Bs 1960 a, 1960 b, 1960 c may implement MIMOtechnology. Thus, the eNode-B 1960 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 1902 a.

Each of the eNode-Bs 1960 a, 1960 b, 1960 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 19D, theeNode-Bs 1960 a, 1960 b, 1960 c may communicate with one another over anX2 interface.

The core network 1907 shown in FIG. 19D may include a mobilitymanagement gateway (MME) 1962, a serving gateway 1964, and a packet datanetwork (PDN) gateway 1966. While each of the foregoing elements aredepicted as part of the core network 1907, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 1962 may be connected to each of the eNode-Bs 1960 a, 1960 b,1960 c in the RAN 1904 via an S1 interface and may serve as a controlnode. For example, the MME 1962 may be responsible for authenticatingusers of the WTRUs 1902 a, 1902 b, 1902 c, beareractivation/deactivation, selecting a particular serving gateway duringan initial attach of the WTRUs 1902 a, 1902 b, 1902 c, and the like. TheMME 1962 may also provide a control plane function for switching betweenthe RAN 1904 and other RANs (not shown) that employ other radiotechnologies, such as GSM or WCDMA.

The serving gateway 1964 may be connected to each of the eNode Bs 1960a, 1960 b, 1960 c in the RAN 1904 via the S1 interface. The servinggateway 1964 may generally route and forward user data packets to/fromthe WTRUs 1902 a, 1902 b, 1902 c. The serving gateway 1964 may alsoperform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when downlink data isavailable for the WTRUs 1902 a, 1902 b, 1902 c, managing and storingcontexts of the WTRUs 1902 a, 1902 b, 1902 c, and the like.

The serving gateway 1964 may also be connected to the PDN gateway 1966,which may provide the WTRUs 1902 a, 1902 b, 1902 c with access topacket-switched networks, such as the Internet 1910, to facilitatecommunications between the WTRUs 1902 a, 1902 b, 1902 c and IP-enableddevices.

The core network 1907 may facilitate communications with other networks.For example, the core network 1907 may provide the WTRUs 1902 a, 1902 b,102 c with access to circuit-switched networks, such as the PSTN 1908,to facilitate communications between the WTRUs 1902 a, 1902 b, 1902 cand traditional land-line communications devices. For example, the corenetwork 1907 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 1907 and the PSTN 1908. In addition, the corenetwork 1907 may provide the WTRUs 1902 a, 1902 b, 1902 c with access tothe networks 1912, which may include other wired or wireless networksthat are owned and/or operated by other service providers.

FIG. 19E is a system diagram of the RAN 1905 and the core network 1909according to another embodiment. The RAN 1905 may be an access servicenetwork (ASN) that employs IEEE 802.16 radio technology to communicatewith the WTRUs 1902 a, 1902 b, 1902 c over the air interface 1917. Aswill be further discussed below, the communication links between thedifferent functional entities of the WTRUs 1902 a, 1902 b, 1902 c, theRAN 1905, and the core network 1909 may be defined as reference points.

As shown in FIG. 19E, the RAN 1905 may include base stations 1980 a,1980 b, 1980 c, and an ASN gateway 1982, though it will be appreciatedthat the RAN 1905 may include any number of base stations and ASNgateways while remaining consistent with an embodiment. The basestations 1980 a, 1980 b, 1980 c may each be associated with a particularcell (not shown) in the RAN 1905 and may each include one or moretransceivers for communicating with the WTRUs 1902 a, 1902 b, 1902 cover the air interface 1917. In one embodiment, the base stations 1980a, 1980 b, 1980 c may implement MIMO technology. Thus, the base station1980 a, for example, may use multiple antennas to transmit wirelesssignals to, and receive wireless signals from, the WTRU 1902 a. The basestations 1980 a, 1980 b, 1980 c may also provide mobility managementfunctions, such as handoff triggering, tunnel establishment, radioresource management, traffic classification, quality of service (QoS)policy enforcement, and the like. The ASN gateway 1982 may serve as atraffic aggregation point and may be responsible for paging, caching ofsubscriber profiles, routing to the core network 1909, and the like.

The air interface 1917 between the WTRUs 1902 a, 1902 b, 1902 c and theRAN 1905 may be defined as an R1 reference point that implements theIEEE 802.16 specification. In addition, each of the WTRUs 1902 a, 1902b, 1902 c may establish a logical interface (not shown) with the corenetwork 1909. The logical interface between the WTRUs 1902 a, 1902 b,1902 c and the core network 1909 may be defined as an R2 referencepoint, which may be used for authentication, authorization, IP hostconfiguration management, and/or mobility management.

The communication link between each of the base stations 1980 a, 1980 b,1980 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 190 a, 1980b, 1980 c and the ASN gateway 1982 may be defined as an R6 referencepoint. The R6 reference point may include protocols for facilitatingmobility management based on mobility events associated with each of theWTRUs 1902 a, 1902 b, 1900 c.

As shown in FIG. 19E, the RAN 1905 may be connected to the core network1909. The communication link between the RAN 105 and the core network1909 may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 1909 may include a mobile IP home agent(MIP-HA) 1984, an authentication, authorization, accounting (AAA) server1986, and a gateway 1988, While each of the foregoing elements aredepicted as part of the core network 1909, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA 1984 may be responsible for IP address management, and mayenable the WTRUs 1902 a, 1902 b, 1902 c to roam between different ASNsand/or different core networks. The MIP-HA 1984 may provide the WTRUs1902 a, 1902 b, 1902 c with access to packet-switched networks, such asthe Internet 1910, to facilitate communications between the WTRUs 1902a, 1902 b, 1902 c and IP-enabled devices. The AAA server 1986 may beresponsible for user authentication and for supporting user services.The gateway 1988 may facilitate interworking with other networks. Forexample, the gateway 1988 may provide the WTRUs 1902 a, 1902 b, 1902 cwith access to circuit-switched networks, such as the PSTN 1908, tofacilitate communications between the WTRUs 1902 a, 1902 b, 1902 c andtraditional land-line communications devices. In addition, the gateway1988 may provide the WTRUs 1902 a, 1902 b, 1902 c with access to thenetworks 1912, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

Although not shown in FIG. 19E, it will be appreciated that the RAN 1905may be connected to other ASNs and the core network 1909 may beconnected to other core networks. The communication link between the RAN1905 the other ASNs may be defined as an R4 reference point, which mayinclude protocols for coordinating the mobility of the WTRUs 1902 a,1902 b, 1902 c between the RAN 1905 and the other ASNs. Thecommunication link between the core network 1909 and the other corenetworks may be defined as an R5 reference, which may include protocolsfor facilitating interworking between home core networks and visitedcore networks.

The processes described above may be implemented in a computer program,software, and/or firmware incorporated in a computer-readable medium forexecution by a computer and/or processor. Examples of computer-readablemedia include, but are not limited to, electronic signals (transmittedover wired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, UE, terminal, base station, RNC, and/or any host computer.

1-24. (canceled)
 25. An apparatus for video decoding, comprising: aprocessor configured to: obtain intra prediction mode informationassociated with a video block; determine an intra prediction mode of aplurality of intra prediction modes based on the obtained intraprediction mode information; obtain a subsampled sub-block of the videoblock based on the determined intra prediction mode of the plurality ofintra prediction modes, wherein the subsampled sub-block comprisespixels from two or more rows and two or more columns of the video block;obtain parameters associated with one or more remaining sub-blocks ofthe video block; and decode the one or more remaining sub-blocks of thevideo block based on the obtained subsampled sub-block, the determinedintra prediction mode of the plurality of intra prediction modes, andthe obtained parameters associated with the one or more remainingsub-blocks of the video block.
 26. The apparatus of claim 25, whereinthe intra prediction mode information comprises an intra prediction modetype.
 27. The apparatus of claim 25, wherein the parameters associatedwith the one or more remaining sub-blocks of the video block aresignaled in video data.
 28. The apparatus of claim 25, wherein theparameters are further associated with the subsampled sub-block of thevideo block.
 29. The apparatus of claim 25, wherein the subsampledsub-block and the one or more remaining sub-blocks are comprised in onevideo frame.
 30. The apparatus of claim 25, wherein the subsampledsub-block of the video block comprises luma samples.
 31. The apparatusof claim 25, wherein the video block comprises chroma samples, thesubsampled sub-block and the one or more remaining sub-blocks arecomprised in one video frame, and the processor is further configured topredict the one or more remaining sub-blocks of the video block based onthe obtained subsampled sub-block, wherein the one or more remainingsub-blocks of the video block are decoded based on the prediction of theone or more remaining sub-blocks of the video block.
 32. A method forvideo decoding, comprising: obtaining intra prediction mode informationassociated with a video block; determining an intra prediction mode of aplurality of intra prediction modes based on the obtained intraprediction mode information; obtaining a subsampled sub-block of thevideo block based on the determined intra prediction mode of theplurality of intra prediction modes, wherein the subsampled sub-blockcomprises pixels from two or more rows and two or more columns of thevideo block; obtaining parameters associated with one or more remainingsub-blocks of the video block; and decoding the one or more remainingsub-blocks of the video block based on the obtained subsampledsub-block, the determined intra prediction mode of the plurality ofintra prediction modes, and the obtained parameters associated with theone or more remaining sub-blocks of the video block.
 33. The method ofclaim 32, wherein the intra prediction mode information comprises anintra prediction mode type, and wherein the subsampled sub-block of thevideo block comprises luma samples.
 34. The method of claim 32, whereinthe parameters associated with the one or more remaining sub-blocks ofthe video block are signaled in video data.
 35. The method of claim 32,wherein the parameters are further associated with the subsampledsub-block of the video block, and wherein the subsampled sub-block andthe one or more remaining sub-blocks are comprised in one video frame.36. The method of claim 32, wherein the video block comprises chromasamples, the subsampled sub-block and the one or more remainingsub-blocks are comprised in one video frame, and the method furthercomprises predicting the one or more remaining sub-blocks of the videoblock based on the obtained subsampled sub-block, wherein the one ormore remaining sub-blocks of the video block are decoded based on theprediction of the one or more remaining sub-blocks of the video block.37. An apparatus for video encoding, comprising: a processor configuredto: determine an intra prediction mode of a plurality of intraprediction modes; obtain a subsampled sub-block of a video block basedon the determined intra prediction mode of the plurality of intraprediction modes, wherein the subsampled sub-block comprises pixels fromtwo or more rows and two or more columns of the video block; obtainparameters associated with one or more remaining sub-blocks of the videoblock; and encode the one or more remaining sub-blocks of the videoblock based on the obtained subsampled sub-block, the determined intraprediction mode of the plurality of intra prediction modes, and theobtained parameters associated with the one or more remaining sub-blocksof the video block.
 38. The apparatus of claim 37, wherein thesubsampled sub-block of the video block comprises luma samples.
 39. Theapparatus of claim 37, wherein the parameters are further associatedwith the subsampled sub-block of the video block, and wherein thesubsampled sub-block and the one or more remaining sub-blocks arecomprised in one video frame.
 40. The apparatus of claim 37, wherein thevideo block comprises chroma samples, the subsampled sub-block and theone or more remaining sub-blocks are comprised in one video frame, andthe processor is further configured to predict the one or more remainingsub-blocks of the video block based on the obtained subsampledsub-block, wherein the one or more remaining sub-blocks of the videoblock are encoded based on the prediction of the one or more remainingsub-blocks of the video block.
 41. A method for video encoding,comprising: determining an intra prediction mode of a plurality of intraprediction modes; obtaining a subsampled sub-block of a video blockbased on the determined intra prediction mode of the plurality of intraprediction modes, wherein the subsampled sub-block comprises pixels fromtwo or more rows and two or more columns of the video block; obtainingparameters associated with one or more remaining sub-blocks of the videoblock; and encoding the one or more remaining sub-blocks of the videoblock based on the obtained subsampled sub-block, the determined intraprediction mode of the plurality of intra prediction modes, and theobtained parameters associated with the one or more remaining sub-blocksof the video block.
 42. The method of claim 41, wherein the subsampledsub-block of the video block comprises luma samples.
 43. The method ofclaim 41, wherein the parameters are further associated with thesubsampled sub-block of the video block, and wherein the subsampledsub-block and the one or more remaining sub-blocks are comprised in onevideo frame.
 44. The method of claim 41, wherein the video blockcomprises chroma samples, the subsampled sub-block and the one or moreremaining sub-blocks are comprised in one video frame, and the methodfurther comprises predicting the one or more remaining sub-blocks of thevideo block based on the obtained subsampled sub-block, wherein the oneor more remaining sub-blocks of the video block are encoded based on theprediction of the one or more remaining sub-blocks of the video block.